Epistle

'An epistle' - pronounced with the 't' silent, IPA: /ɪ 'pɪ səl/ - means 'a letter', in the sense of a written communication or message. It derives from the Greek word ἐπιστολή (epistole, ‘message’, ‘letter’). The word 'epistle' is rarely used in current English except in reference to the letters in the New Testament written by the Apostles to the scattered congregations of Christians. 'The Epistle' is a reading from one of these during, and as part of, a church service.

AWE has a list of all the Epistles in the Bible, included in the list of all the Books of the Bible.

You may also see the word used for certain verse compositions by, or in imitation of, classical Latin or Greek authors. Otherwise, its use nowadays is nearly always jocular.

The adjective from ‘epistle’ is ‘epistolary’, pronounced with the stress on the second syllable, IPA: / ɪ 'pɪ stə lə rɪ/, or (a secondary but still accepted pronunciation) with the stress shifted to the third syllable 'ep-ist-OLL-er-y', /ˌɛp ɪst ˈɒl ər ɪ/. For example, a novel written in the form of a series of letters may be described as an epistolary novel.